Girolano Cardano

Cardano, Girolamo (1501–76)

The Renaissance Italian Girolamo Cardano is famous for his colourful personality, as well as for his work in medicine and mathematics, and indeed in almost all the arts and sciences. He was an eclectic philosopher, and one of the founders of the so-called new philosophy of nature developed in the sixteenth century. He used both the Aristotelian and the Neoplatonic traditions as starting points, and following the medical paradigm of organic being, he transformed the traditional Aristotelian universe into an animated universe in which, thanks to their organic functional order, all individual parts strive towards the conservation both of themselves and of the whole universe. As a result, they can be subjected to a functional analysis. In his more casual writings on moral philosophy, Cardano showed his orientation to be basically Stoic.

1 Life

Girolamo Cardano (also known as Gerolamo Cardano or Hieronymus Cardanus) was the illegitimate son of a Milanese lawyer, and grew up in very difficult conditions. He studied medicine and mathematics at Pavia (1518–23) and Padua (1524–6). He received his MA and his MD from Padua, and practised as a physician, first at Saccolongo near Padua (1526–32) and then, after some controversy with his local colleagues, in Milan (1539–43). In 1552 he successfully cured John Hamilton, Bishop of Edinburgh, of asthma, and for the rest of his life enjoyed his reputation as a famous physician. Cardano started teaching mathematics at Milan in 1534, and medicine in Pavia from 1543. After the execution of his son for murder Cardano left Pavia, and he taught at Bologna from 1562. He was arrested by the Inquisition in 1570 for reasons which remain unknown, and was released on condition that he abandon teaching and publishing. Cardano then went to Rome where he received an annuity from the Pope, and continued to practise as a physician. He also worked on his frank and self-revelatory autobiography up to the time of his death on 21 September 1576, a date that he had himself foretold from his horoscope.

Cardano was a prolific writer. In his will of 1571 he mentions 103 printed works and forty-three in manuscript form. In his autobiography De vita propria liber (The Book of My Life) he counts fifty-five works in print and forty-five in manuscript. His Opera omnia contains seventy-one works published during his lifetime and forty other works. His style is inelegant, his Latin faulty, his argumentation often incomplete and disorganized, and as a result his writings are often unclear and difficult to understand. This does not, however, mean that he had nothing of value to say.

2 Non-philosophical achievements

Cardano was extremely creative, and a torchbearer for scientific progress. He took pride in being called vir inventionum (the man of inventions) and opened up new perspectives on every field he entered. In medicine, Cardano claimed to have made 40,000 important and 200,000 less important inventions. In mathematics, he taught a method for solving cubic equations, though the mathematician Tartaglia accused him of plagiarism, and he made the first moves towards the theory of probability. In mechanics ‘Cardano’s suspension’ is still regarded as a success. He wrote on music and on dreams, believed in demons, and was regarded as a reliable astrologer, who even cast the horoscope of Jesus Christ.

3 Metaphysics

Cardano claimed that Plotinus and Aristotle were his main inspiration in philosophy, and though he argued explicitly against Aristotle, his theory is implicitly based on the Aristotelian tradition. While he was not a systematic thinker, his work rests on some basic assumptions which allow for a systematic understanding of his main philosophical teaching, and which are themselves of major philosophic interest.

His notion of unity is fundamental. It was developed in a little treatise De uno (On the One), written around 1560 and published in Basle in 1562. Cardano himself recommended it as an introduction to his natural philosophy. In it he argued that everything that exists is one, so that the structure of unity is identical to the structure of reality. Analysis of a given real being, a human being for example, shows that its unity consists both in the single principle behind its various operations and in the organic structure of its corporeal basis, which guarantees that its various parts cooperate in the effort to achieve self-conservation. Thus every real being can properly be regarded as a system constituted by a certain number of organic parts that cooperate in function. Every organ, in so far as it is a real being and therefore one, has necessarily to be such a system; and every real being, as part of a greater, more comprehensive, whole, has to function as an organ of this larger unit. As a result, reality is reduced to a system of functions, in which every individual being is at the same time an organ or subsystem of its supersystem, and the superior unit of its subsystems. This kind of ordering is also to be found in the sphere of history, which is governed by fate.

4 Physics

In Cardano’s treatise De natura (On Nature), written at the same time as De uno (though not published in his lifetime) and like De uno recommended as introductory reading, Cardano developed his concept of nature in accordance with his basic ontological principle of unity. The single principle which coordinates the various operations of natural beings and causes the organic order of their unity is called the soul. As a result the whole of the material world is animated, and Aristotle’s distinction between organic and non-organic nature is abandoned. Different souls are systematically ordered in the same way as the different natural beings which they animate. Their principal task is to care for the self-preservation of the bodies which correspond to them, so they are endowed with whatever means of cognition are necessary for that task. They act in accordance with the principles of sympathy and antipathy. The intellectual soul, being supernatural, is one and the same for all human beings, as Averroes had held (see Ibn Rushd §3).

Bodies themselves are constituted by the heat of the heavens. This heat is the active principle that serves the soul, and operates on the passive principle’s density or extension. In De subtilitate (On Subtlety) Cardano identifies this passive principle with prime matter (prima materia) which, according to Averroes, is endowed with indefinite quantity; in De natura the passive principle is understood as moisture. Thus Cardano reduces and transforms Aristotle’s doctrine of the four primary qualities (hot, cold, wet and dry) that constitute the four elements.

5 Epistemology

Natural beings are perceived as organic units through the senses, and it is the task of science, through a functional analysis, to transform this confused knowledge of the whole into a distinct knowledge of its parts and their ordering in a system. Thanks to the infinity of the universe’s various parts, human beings will never be able to analyse and thereby know the whole of the universe. Moreover, thanks to the infinite subtlety of the smallest parts, which escape the senses, these too will necessarily remain unknown. As a result, as Cardano points out in De arcanis aeternitatis (On the Secrets of Eternity), it is the greatest and indeed most disastrous error to claim that humans can achieve absolute knowledge. Nonetheless, there are organic units which are not disproportionate to the human intellect in terms of the variety of their parts and the subtlety of their structure, and these can be the subject of scientific analysis. Moreover, they enjoy ontological autonomy as far as their place in the system’s order is concerned, and hence can be known, if not according to their essence, at least according to their functional structure. It is this knowledge of the functional structure of natural beings that, if soundly based, can be used in technical or mechanical inventions.

6 Main works in natural philosophy

It is in the context of the principles discussed in §§3–5 that Cardano’s main works in natural philosophy, the twenty-one books of De subtilitate from 1550, and their supplement, the seventeen books of De rerum varietate (On the Variety of Beings) written in 1557, should be read. While their titles refer to the aspects of reality that constitute the limits of human knowledge, the books themselves offer a comprehensive description of the whole universe. Following the order of the traditional Aristotelian doctrine of nature, they start with the principles of physics and descend to the elements, the mixed bodies, metals and stones, plants, animals, and human beings; then they ascend again from the psychological faculties of the senses, the will and the intellect, through their effects, the arts and sciences, to the demons, first substances, and God himself. This apparently Aristotelian order led Julius Caesar Scaliger to criticize Cardano from the perspective of orthodox Aristotelianism; the fact that, for no apparent reason, Cardano mixed the theoretical with the practical and the general with the particular does make it difficult to follow his arguments. However, contrary to Scaliger’s belief, Cardano did not intend to teach Aristotelian natural philosophy. Nor did he, contrary to modern expectations, intend to display a comprehensive and consistent theory of nature. His way of writing and arguing must be understood in the light of his denial of the possibility of absolute truth and his doubts about the fruitfulness of merely theoretical argumentation. He was content to offer a functional analysis of individual natural beings through sense perception, and to validate his analysis through technical application.